The present invention relates to a muffler for internal combustion engine.
Generally speaking, the muffler attached to internal combustion engine is heated to a considerably high temperature during the operation of the engine. For instance, in the case of small-sized air-cooled 2-cycle internal combustion engines, the temperature of exhaust gas flowing through the muffler well reaches 600.degree. to 700.degree. C. so that the muffler itself is heated to develop a high temperature of 300.degree. to 400.degree. C. at the surface thereof to exhibit a considerable thermal distortion. Such a thermal distortion does not cause substantial problem when the body of the muffler is fixed to the body of the internal combustion engine only at one portion thereof because, in such a case, the thermal distortion is effectively absorbed at the free end of the muffler body but various problems are caused when the muffler body is fixed at a plurality of portions thereof. The problem is serious particularly in opposed twin type engine in which only one muffler is connected commonly to two cylinders which are arranged horizontally opposite one another. Namely, in such a case, the muffler is connected to the exhaust ports of two cylinders spaced from each other so that the thermal distortion of the muffler during operation of the engine cannot be absorbed and a force is applied to the muffler to forcibly stretch the muffler at the portion thereof between the two points where the muffler is connected to the exhaust ports of the cylinders. In consequence, relative positions of various parts are changed undesirably. Such changes in the relative positions, although they may be slight, causes various troubles such as local wear of cylinders and pistons, seizure, abnormal vibration, leak of compressed gas and so forth.